Horizontal axis wind turbine comprising families of blades
The invention relates to a wind turbine that includes a rotor rotating about a horizontal axis of rotation substantially parallel to the direction of the wind, the rotor having a front face facing into the wind and substantially perpendicular to the axis of the wind, and a rear face situated toward a support of the rotor. At least two distinct families of blades are distributed on the rotor, each family of blades including at least two blades having a free end and a blade root end connected to said rotor. Each family of blades includes a catching blade guiding the wind toward a force blade having a surface arranged substantially perpendicular to the axis of the wind, the blade root ends of each family of blades are successively offset on an exterior surface of the rotor along the axis of rotation thereof.
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This application claims priority to International Application No. PCT/FR2014/052638 filed Oct. 16, 2014 and to French Application No. 1360206 filed Oct. 18, 2013: the entire contents of each are incorporated herein by reference.
1. FIELD OF THE INVENTIONThe present invention relates to the field of electrical energy production. It is aimed in particular at a wind turbine with a horizontal axis of rotation substantially parallel to the direction of the wind, used to convert the kinetic energy of the wind into mechanical energy which will itself be converted into electrical energy.
2. PRIOR ARTThese days, in order to obtain greater technical and energy performance, experts in this field are proposing wind turbines equipped with blades of increasingly great length. The blade span of these wind turbines does not really suit the landscape because of the unsatisfactory esthetic appearance and the large size thereof. These wind turbines also require considerable logistics and extraordinary infrastructures in order to transport the components and assemble them, particularly in the case of offshore wind turbines.
The largest span (between 70 meters and 130 meters (m)) may reach nominal powers of between 2 and 7 megawatts at a windspeed in a range from 9 to 15 meters per second (medium wind). Above and below this range the wind turbines do not produce more energy. However, in order to increase their efficiency, wind turbines intended to produce a power of 10 megawatts (MW) with expected spans of 140 meters, namely the equivalent of 2 A380® airplanes side by side, are under development.
In strong winds, notably winds above 15 m/s, the crucial factor is the integrity of the wind turbine (reliability, robustness, stress loadings) rather than the energy efficiency thereof. Although the torque can be improved, the limiting factor is the laws of physics regarding the power coefficient (Cp) (the ratio between the energy supplied by the wind turbine with respect to the energy of the wind entering the surface swept by the blades). The upper production limit (maximum nominal power) is generally reached between 12 and 15 m/s (45 to 55 km/h), at which point the wind capacity captured at the blade tip and across the entire swept surface is then maximized. Added to this matter is the fact that beyond their nominal operating ranges, their power coefficient (Cp) begins to drop off drastically; wind turbines are slowed down in order to maintain the maximum nominal power already achieved.
Upwards of 25 m/s (storms, hurricanes), the mechanical stress loadings applied by the wind to the wind turbines and notably to the blades become very high and most wind turbines are automatically shut down in order to protect them. Upward of 25 m/s there is a risk of compromising the integrity of the wind turbines and a very high risk of breakage. In the onshore market, the noise and stormy episodes are factors that justify disconnection from the network well before excessively high winds arrive.
3. OBJECTIVES OF THE INVENTIONIt is a notable objective of the invention to alleviate all or some of the disadvantages of the prior art.
One objective of the invention is to provide a wind turbine capable of operating in any type of wind, more specifically by providing better efficiency amongst other things under light wind and strong wind conditions.
In particular, one objective of the invention is to provide a wind turbine that produces more mechanical power as compared with a conventional wind turbine with an equivalent span or a wind turbine that produces equivalent mechanical power with a span that is reduced in comparison with a conventional wind turbine.
Yet another objective of the invention is to reduce the effect of shear and wake turbulence to the rear of the wind turbine that forces wind turbines of a wind farm to be spaced away from their neighbors. In other words, to allow the wind farms to be more densely populated with turbines.
4. SUMMARY OF THE INVENTIONThese objectives are achieved using a wind turbine comprising:
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- a rotor for rotating about a horizontal axis of rotation substantially parallel to the direction of the wind, the rotor having a front face facing into the wind and said face being substantially perpendicular to the direction of the wind, and a rear face situated toward a support of the rotor; and
- at least two distinct families of blades distributed over the rotor, each family of blades comprising at least three blades having a free end and a blade root end connected to said rotor; each family of blades comprising a catching blade guiding the wind toward a guide blade which guides the wind toward a force blade having a surface arranged substantially perpendicular to the direction of the wind, the blade root ends of the blades of each family of blades being successively offset on an exterior surface of the rotor along its axis of rotation and the catching blade has a length that is reduced in comparison with the guide blade which itself has a length that is reduced in comparison with the force blade.
Thus, such a configuration of families of blades makes it possible to supply a wind turbine that has a blade surface area substantially identical to that of a conventional wind turbine comprising very long blades by increasing the number of blades in a family. The same mechanical surface area facing into the wind is represented by the physical dimensions of the blades in a family. The surface of the blades is swept by the wind for a longer duration than conventional blades. The wind thus guided exerts a maximum thrusting force that is uninterrupted whatever the windspeed. The blades have the ability to accelerate with a light wind and notably with a strong wind. The arrangement of these blades therefore makes it possible to increase the efficiency that will need to compensate for part of the loss of moment (blade length*wind strength) at the blade tip (the blade-tip lever arm is lower when the blade lengths are reduced in comparison with a conventional wind turbine). Such an arrangement also makes it possible to reduce the span of the blades thus allowing the wind farm to be more densely populated with wind turbines. By, for example, halving the span in order to have an efficiency equivalent to a conventional wind turbine, the number of wind turbines in the same surface area, which in general is limited, can be doubled thus doubling the efficiency of a wind farm with respect to an exploitable area.
According to one particular feature of the invention, the catching blade may be positioned in front of the force blade along the axis of rotation of the rotor so as to create a different windage. The blades arranged in this way therefore behave a little like a succession of sailboat sails. Advantageously, the catching blade may be smaller in length but have a width that is greater than that of the force blade. The catching blade encounters the wind in the direction in which the wind is blowing and will seek to guide the first wind toward the next blade which is longer and will therefore enjoy a greater lever arm; the arrangement of these families will therefore make it possible to create microzones of depression encouraging the acceleration of the subsequent blades, making the drag only the consequence of the length of the next blade and creating coherence between the windspeed and the acceleration of the rotor and blade families assembly (under conditions of strong wind, the rotor and blade families assembly still has the capacity to accelerate in comparison with a conventional wind turbine). There is therefore less of a windbreak effect and that contributes to reducing the effects of wake behind the wind turbine.
According to one embodiment, each blade root end may be arranged on the surface of the rotor at a predetermined angle α formed between the axis of rotation of the rotor and the direction of the blade root end in order to better guide the wind onto the subsequent blades of each family.
In particular, the blades stand out from the rotor in a longitudinal direction that forms a predetermined angle β with the surface of the rotor. In that way, the position of the blades on the rotor, combined with their orientation (blades angled) allow the wind to be concentrated toward the inside of the blades. In addition, such a configuration makes it possible to reduce the effects of turbulence which no longer acts on one blade at a time as in a conventional wind turbine, but acts on the entire family of blades.
Advantageously, the predetermined angle α or β is greater than 0° and less than or equal to 90°.
According to another embodiment, the wind turbine comprises movement means moving the families of blades between: an initial position in which the families of blades are close to the horizontal axis of the rotor; and a developed position in which the families of blades are situated some distance from the horizontal axis of the rotor. In that way, the wind turbine is capable of operating in the case of light and strong winds and of being made safe at the same time notably in the case of strong winds.
Still with the same aim, the movement means cause the arrangement of the families of blades to vary in a movement that is:
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- radial with respect to the axis of rotation of the rotor; and/or
- translational, substantially parallel to the surface of the rotor in a direction oriented from the rear face toward the front face or vice versa.
The movement means may be installed in or outside the rotor.
According to this embodiment, each family of blades is mounted on a single support connected to the movement means thereby making it possible easily to move the entire family of blades at the same time.
According to one alternative form of this embodiment and another embodiment, each family 8 of blades is mounted on a support comprising a base sliding along guide rails, said guide rails being arranged on a profiled section of a structure positioned in the rotor, the profiled section being connected to the movement means.
According to another embodiment, the structure comprises at least the profiled section provided with a first end and with a free second end, the profiled section being arranged between a first platform having an internal surface and a second platform to which the first end is articulated so that the profiled section is able to move between an operational first position in which the free second end lies flush with the surface and a feathered position in which the free second end is situated some distance from the surface via the movement means.
Advantageously, the support comprises means of setting the support in rotation with respect to the surface of the rotor about an axis of rotation passing through a root of the support at an angle of between 0° and 360°.
According to another embodiment of the invention, the wind turbine may comprise guide means which move each blade of a family substantially in a rotation about the axis of rotation of the rotor between an initial position in which the blades are close to the axis of rotation, and a retracted position in which the blades are close to the axis of rotation placed behind one another. This configuration makes it possible to increase the air that escapes between the families of blades and to reduce the windage on the blades in the event of strong winds, for example with respect to the swept surface of the (rotating) force blade.
According to another particular feature of these aforementioned embodiments, the rotor may comprise a wall comprising through-openings extending longitudinally from the front face toward the rear face of the rotor or extending in a curve comprising a first portion extending substantially longitudinally from the front face toward the rear face and a second portion extending in a direction substantially parallel to the direction of the blade root end of the force blade.
Advantageously, each through-opening is designed to receive at least one element connected to the movement means or guide means passing through the through-opening between the initial position and the deployed or retracted position.
Advantageously, the movement means or the guide means may comprise at least one hydraulic actuator or a worm that can be driven by an electric motor.
According to another embodiment, the rotor may have a cylindrical or frustoconical section. A cylindrical rotor allows the blades to be distributed suitably thereover. In the case of a rotor of frustoconical section, the objective of this configuration is to force the wind to cover a greater distance than with a conventional rotor. In addition, the thrusting force of the wind is better distributed from the blade root end to the free end of the blades, thereby improving the efficiency of the wind turbine and affording it greater stability.
Further innovative advantages and features will become apparent from the description given hereinafter, provided by way of nonlimiting indication with reference to the attached drawings in which:
The present invention relates to a wind turbine 1 designed to operate in any type of wind, namely under light-wind, medium-wind and strong-wind conditions. In the remainder of the description:
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- light wind means a wind the windspeed of which is between 0 and 5 to 7 m/s meters per second (m/s);
- medium wind means a wind the windspeed of which is between 5 to 7 m/s and 10 to 15 m/s;
- strong wind means a wind of which the windspeed is above 15 m/s; and
- violent wind (storms, hurricane) means a wind the windspeed of which is above 25 m/s.
In
In order to make the invention even easier to understand, it will be considered that the mast 2 extends in a vertical longitudinal direction Z. Also depicted is the transverse horizontal direction Y in which the axis of rotation 15 of the rotor 5 extends, which axis is perpendicular to the vertical longitudinal direction Z and to a longitudinal direction X such that these three directions X, Y, Z form a direct orthogonal frame of reference as depicted in
The terms “lower”, “upper”, “top”, “bottom” and “lateral” are defined with respect to the vertical direction Z and the terms “front” and “rear” are defined with respect to the direction Y.
The rotor 5 has a front face 6 facing into the wind and substantially perpendicular to the direction of the wind, a rear face 7 situated toward a support of the rotor 5 and an external surface 12. In reality, the rear face 7 faces toward the nacelle 4. The expression substantially perpendicular means perpendicular or substantially perpendicular. The front face 6 may have a nose cone 111 of oblong shape to improve the aerodynamics of the rotor 5.
According to the embodiment illustrated in
In the various embodiments illustrated, a rotor 5 bears three families 8 of blades 9 distributed over the rotor 5 at an angle of 120°. Each family 8 comprises three blades 9. Each blade 9 has a free end 10 and a blade root end 11 connected to the rotor 5. Each blade 9 of a family has dimensions, an implantation, an orientation and/or a function that differ from those of the other blades. Each family includes: a catching blade 9a, a guide blade 9b and a force blade 9c. The wind is first of all caught by the catching blade 9a. The latter captures the wind then guides it toward the guide blade 9b. The guide blade 9b also guides the wind toward the force blade 9c on which the wind builds up. With this arrangement, the wind is trapped and can escape only by applying a thrusting force F to the blades 9a, 9b, 9c in turn. It will therefore be appreciated that the guide blade 9b is positioned in front of the force blade 9c along the axis 15 of rotation of the rotor 5. The catching blade 9a is positioned in front of the guide blade 9b along the axis 15 of rotation of the rotor 5. In that way, by forcing the wind to transmit its kinetic energy three times (or n times, n being the number of blades in a family), the time that the wind passes through the families 8 of blades is increased. If there are n blades in a family 8 where n is greater than three, then all the blades 9 situated between the catching blade 9a and the force blade 9c are guide blades 9b. Between each adjacent family 8 of blades 9 there is a space corresponding to an exhaust zone 34 via which some of the air (wind) escapes from the wind turbine 1. More specifically, the exhaust zone 34 is formed between the blade root end 11 till the free end 10 of the catching blade 9a of one family 8 and the blade root end 11 till the free end 10 of the force blade 9c of an adjacent family 8 of blades. As shown in
The catching blade 9a has a length that is reduced in comparison with the guide blade 9b, which itself has a length that is reduced in comparison with the force blade 9c. In other words, the blades 9a, 9b, 9c of each family 8 have dimensions that increase along the axis 15 of rotation of the rotor 5 from the front face 6 toward the rear face 7 of the rotor 5. Furthermore, as shown in
Each blade 9 also has a flat surface 13 as depicted in
As mentioned earlier, each blade 9a, 9b, 9c of each family 8 of blades 9 has an implantation and a particular orientation on the rotor 5; these are described according to an embodiment depicted in
In
Wind turbines 1 that are small in size and not very bulky, and medium-sized wind turbines 1 or wind turbines that have the dimensions of a conventional wind turbine are catered for. As far as the small wind turbines are concerned, the rotor 5 and the blades 9 are formed of a single piece as illustrated in
According to other embodiments depicted in
Movement means 23 are provided to move the families 8 of blades 9 between an initial position in which the families 8 of blades are close to the horizontal axis 15 of rotation of the rotor 5 (close to the front face 6) and a developed position in which the families 8 of blades 9 are situated some distance from the axis of rotation 15 of the rotor 5 (close to the rear face 7). In the initial position, the movement means 23 comprise at least one actuator 32 or worm. For preference, these are actuators 32 each comprising a cylinder 25 in which a piston 26 and rod 27 assembly slides.
The wind turbine 1 referred to as dynamic comprises a structure 19 as depicted for example in
The families 8 of blades are each mounted on the support 24 connected at least to the movement means 23. In that way, in a movement, it is the support 24 that moves causing simultaneous movement of the families 8 of blades 9. The support 24 is positioned on the external surface 12 of the rotor 5 and is able to move with respect to this surface. The support 24 comprises a root 58 supporting a mounting plate 57 at one of its ends 59.
The mounting plate 57 (for example in
The wall 33 of the rotor 5 comprises through-openings 28 and 28″ passing right through the wall 33.
According to the embodiments of
When the force applied by the wind is above a predetermined force, a microcontroller commands the electric motor 42 which then actuates the actuators 32 in order to move the families of blades. When the piston 26 moves in the cylinder 25, the rod 27 drives the arm 29 in a translational movement through the longitudinal through-opening 28.
In
In
In a preferred alternative form of this embodiment, the actuators 32 are able to be mobile through the mere thrust of the wind (without the action of the motor 42) in order to move the families 8 of blades 9 via the support 24. The families 8 of blades 9 therefore move from the initial position toward the developed position using the thrust of the wind applied to the blades 9. The families 8 of blades 9 return to the initial position under the effect of their weight. The resistance of the actuator 32 will be calibrated beforehand as desired (implying no external intervention such as electronic, electrical or hydraulic intervention from light winds up to acceptable ranges of operation in strong and not violent winds): the stronger the wind (greater the centrifugal force) the greater will be the resistance of the actuator 32, naturally returning the blades 9 to the down position (initial position) when the wind weakens. The three actuators 32 operate independently, because they are not commanded. Only the thrust of the wind drives them. The rotational speed will mean that the forces experienced by the actuators 32 will be near-identical so that they will react in the same way and at the same time. As mentioned hereinabove in the previous embodiments, the blades 9 of each family 8 maintain their initial positions relative to one another (on the support 24) in accordance with the same configuration as the static wind turbines described previously.
According to another embodiment as may be seen in
The dynamic movement of the blades 9 remains identical to that of the blades of the wind turbines illustrated in
In this embodiment (see
When the hurricane has passed and the checks prior to resumption of operation have been carried out, the operator intervenes physically or remotely on the wind turbine 1 to unblock the profiled sections 22 from their feathered position by unblocking the locking means 71b. The rod 127 of the actuator 100 moves in the opposite direction (the opposite of 70) to return the sliding assembly 43 to a position close to the first platform 20. That allows the families 8 of blades 9 to be returned to the operational position.
The free end 36 then lies flush with the first platform 20 (periphery). As a result, the profiled sections 22 are locked by means of the locking means 71a. The base 60 is unblocked by blocking means 134 so as to allow it to slide along the rails 63.
According to another alternative form of this embodiment illustrated in
For a static wind turbine that is to be brought into a safety position (
In a first alternative form of this embodiment, the base 60 is mounted on a pivoting plate equipped in its lower part with the female component 129 intended to be connected directly to the shaft 128 (no shaft 130 in this alternative form). In order to allow the pivoting plate and the base 60 to rotate, the rail 63 comprises a groove (not depicted) allowing the lower part of the base 60 to pass.
In a preferred second alternative form of this embodiment, the upper part of the shaft 130 is connected to the base 60. In this alternative form, the profiled sections 22 are fixed with respect to the crossmembers 115a, 115b and first and second platforms (
The present wind turbine 1 is perfectly suited to use onshore (particular use: inhabited regions, commercial regions or regions of activity) or to use offshore.
The invention is described in the foregoing by way of example. It must be understood that a person skilled in the art is able to vary the embodiments of the invention in various ways for example by combining the various features above considered alone or in combination, without thereby departing from the scope of the invention.
Claims
1. A wind turbine comprising:
- a rotor for rotating about a horizontal axis of rotation substantially parallel to a direction of wind that is present, the rotor comprising: a front face facing into the wind and substantially perpendicular to the direction of the wind: and a rear face situated toward a support of the rotor; and
- a first family of blades distributed over the rotor, wherein the first family of blades comprises: a first force blade comprising: a first surface arranged substantially perpendicular to the direction of the wind; a first free end; and a first blade root end connected to the first surface and the rotor; a first catching blade guiding the wind toward the first force blade, the first catching blade comprising: a second surface arranged substantially perpendicular to the direction of the wind; a second free end; and a second blade root end connected to the second surface and the rotor, wherein the first force blade is static in being fixed in orientation relative to the rotor and the first catching blade is static in being fixed in orientation relative to the rotor and the first force blade; wherein the first blade root end and the second blade root end are successively offset on an exterior surface of the rotor along the horizontal axis of rotation of the rotor, and the first blade root end and the second blade root end are arranged on the exterior surface of the rotor at a first predetermined angle (α1) and a second predetermined angle (α2), respectively, formed between the horizontal axis of rotation of the rotor and a direction of the first blade root end and the second blade root end, respectively, the first force blade and the first catching blade stand out from the rotor in a longitudinal direction that forms a third predetermined angle (β1) and a fourth predetermined angle (β2) with the exterior surface of the rotor, and each of the first, second, third, and fourth predetermined angles is greater than 0° and less than or equal to 90°; wherein when viewed along the horizontal axis of rotation of the rotor, the first catching blade has a first radial length as measured from the horizontal axis of rotation of the rotor and the first force blade has a second radial length as measured from the horizontal axis of rotation of the rotor, wherein the first radial length is different than the second radial length in magnitude, wherein the first blade root end of the first force blade is less wide than the first free end of the first force blade and the second blade root end of the first catching blade is less wide than the second free end of the first catching blade, wherein the second blade root end of the first catching blade is wider than the first blade root end of the first force blade, and
- a second family of blades distributed over the rotor, wherein the second family of blades is immediately adjacent to and distinct from the first family of blades, the second family of blades comprising: a second force blade connected to the rotor; and a second catching blade guiding the wind toward the second force blade, wherein an exhaust zone is defined between the first force blade and the second catching blade such that no blade exists within the exhaust zone and the exhaust zone subtends an azimuthal angle relative to the horizontal axis of rotation that has a magnitude that is greater than 30°.
2. The wind turbine according to claim 1, wherein the first catching blade is positioned in front of the first force blade along the horizontal axis of rotation of the rotor.
3. The wind turbine according to claim 1, wherein the first family of blades comprises a first guide blade which guides the wind toward the first force blade.
4. The wind turbine according to claim 3, wherein the first radial length of the first catching blade is reduced in comparison with a third radial length of the first guide blade as measured from the horizontal axis of rotation, wherein the third radial length is reduced in comparison with the second radial length of the first force blade as measured from the horizontal axis of rotation.
5. The wind turbine according to claim 3, wherein the second family of blades comprises a second guide blade which guides the wind toward the second force blade.
6. The wind turbine according to claim 5, wherein the second catching blade has a third radial length as measured from the horizontal axis of rotation that is reduced in comparison with a fourth radial length of the second guide blade as measured from the horizontal axis of rotation, wherein the fourth radial length is reduced in comparison with a fifth radial length of the second force blade as measured from the horizontal axis of rotation.
7. The wind turbine according to claim 1, wherein the rotor comprises a cylindrical section.
8. The wind turbine according to claim 1, wherein the second force blade comprises:
- a third surface arranged substantially perpendicular to the direction of the wind;
- a third free end; and
- a third blade root end connected to the third surface and the rotor; and wherein the second catching blade comprises:
- a fourth surface arranged substantially perpendicular to the direction of the wind;
- a fourth free end; and
- a fourth blade root end connected to the fourth surface and the rotor; wherein the third blade root end and the fourth blade root end are successively offset on the exterior surface of the rotor along the horizontal axis of rotation of the rotor, and the third blade root end and the fourth blade root end are each arranged on the exterior surface of the rotor at the first predetermined angle (α) formed between the horizontal axis of rotation of the rotor and a direction of the corresponding blade root end, the second force blade and the second catching blade each stand out from the rotor in a longitudinal direction that forms the second predetermined angle (β) with the exterior surface of the rotor.
9. The wind turbine according to claim 8, wherein the second catching blade is positioned in front of the second force blade along the horizontal axis of rotation of the rotor.
10. The wind turbine of claim 1, wherein the azimuthal angle has a magnitude that is greater than 90°.
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Type: Grant
Filed: Oct 16, 2014
Date of Patent: Jul 19, 2022
Patent Publication Number: 20160237987
Assignee: (Saint Pierre)
Inventor: Sebastien Manceau (Saint Pierre)
Primary Examiner: David E Sosnowski
Assistant Examiner: Aye S Htay
Application Number: 15/030,253
International Classification: F03D 7/02 (20060101); F03D 13/10 (20160101); F03D 1/06 (20060101);